Piston



C, 8. BROWN Jan. 28, 1936.

PISTON Filed Aug. 28, 1951 V 7 a a @MJMMW ATTOR N EYS Patented Jan. 28, 1936 UNITED STATES PATENT OFFICE 2 Claims.

This invention relates to pistons for internal combustion engines and has for its object a piston which is particularly adapted to be used in an aluminum alloy cylinder. Another object is a piston in which the skirt is a separate part from the head and not integrally or rigidly secured thereto but which is secured thereto in order to have a slipping expanding and contracting action circumferentially relatively to the head. 7

The invention consists in the novel features and in the combinations and constructions hereinafter set forth and claimed.

In describing this invention reference is had to the accompanying drawing in which like characters designate corresponding parts in all the views.

Figure 1 is an elevation, partly broken away and partly in section, of this piston.

Figure 2 is an elevation partly broken away and partly in section, taken at a right angle to Figure 1.

Figure 3 is an enlarged fragmentary detail view on the plane of line 3-3, Figure 1.

This piston comprises, generally, a head, and a skirt which is a separate part from the head and connected thereto so that portions thereof have a sliding movement in a circumferential direction relative to the head during expansion and contraction of the skirt differently from the head.

I designates the head which is provided with the usual ring grooves 2 and also with depending piston pin bosses 3. The head is usually cast cupshaped with a diametrically extending reinforcing rib 4 between the pin bosses.

5 is a skirt, this being a sleeve split longitudinally at 6 throughout its entire length and being interlocked with the head at its upper end to have a slipping or sliding movement in a circumferential direction. As here shown, the head is formed with a circumferential channel or groove I and the skirt is formed with an internal flange 8 extending into the groove I and fitting the same with a sliding lit, the channel being comparatively deep and narrow and the flange 8 being of nearly the same width or depth and of the same thickness as the width of the channel, so as to avoid axial movement of the skirt relatively to the head. The skirt and head are secured together to prevent the turning of the skirt relatively to the head and preferably the head is formed with an indentation 9 for receiving an internal projection Ill on the inner side of the sleeve, said projection being formed by indenting the skirt from the outer side thereof,

The skirt is preferably formed of resilient sheet steel, particularly when the piston is to be used in an aluminum alloy cylinder and the skirt is assembled to the head by expanding it over the head so that the flange 8 snaps into the groove I and the diameter of the sleeve is such that the walls of the slot are close together when the piston is fitted into the aluminum alloy cylinder and the sleeve under tension so that it will expand or spring outwardly as the aluminum cylinder becomes heated and expands, all whereby the sheet steel skirt fits the aluminum cylinder at all temperatures, it being understood that aluminum having a greater coefficient of expansion than steel will expand under the influence of heat to a greater degree than steel and that the resiliency of the sheet steel skirt compensates for the difference in the coefficients of expansion between aluminum alloy and the steel. During the expansion and contraction of the skirt, the flange 8 slides relatively to the walls of the groove I.

The pin bosses 3 depend into the upper end of the skirt and the skirt is formed with openings I I. The head I may be formed of aluminum alloy or cast iron or other material.

The openings II are slightly out of alignment with the pin bearin'gs in the pin bosses when the pin is assembled in the bosses; that is, the margin of the Walls around the openings I I lap the ends of the pins in order to hold them from displacement. In assembling the pins in the bosses, the sleeve can be turned to shift the projections I0 out of the depressions 9 until the openings I I are in line with the hearings in the pin bosses, and after the pins have been inserted in the bosses through one of the openings I I, the sleeve or skirt is turned until the projection I0 snaps into the depression 9.

A piston of this character when used in cast iron cylinders may be provided with a skirt consisting of an aluminum sleeve to produce a light weight piston.

What I claim is:

1. A piston for internal combustion engines comprising a head formed with a circumferential groove and a skirt comprising a split sleeve having an internal annular flange located in the groove and slidably engaging the walls thereof, the head having pin bosses depending into the upper end of the skirt and the skirt being formed with openings opposite the pin bosses for permitting the insertion of the piston pins, said skirt being shiftable about the head to bring said openings into alignment with the bearings of the pin bosses and out of alignment th rewith to hold the pins from displacement, and snap catch means for normally holding the skirt from turning about the head.

2. A piston for internal combustion engines comprising a head formed with a circumferential groove and a skirt comprising a split sleeve having an internal annular flange located .in the groove and slidably engaging the walls thereof, the head having pin bosses depending into the upper end of the skirt and the skirt being formed 10 with openings opposite the pin bosses for permitting the insertion of the piston pins, said skirt being shiftable about the head to bring said openings into alignment with the bearings of the pin bosses and out of alignment therewith to hold the pins from displacement, and snap catch means for normally holding the skirt from turning about the head, consisting of a depression in the head and a complemental projection on the skirt.

CHARLES S. BROWN. 

